This invention relates to novel graft copolymers and to a method for their preparation. More particularly, this invention relates to graft copolymers of vinyl monomers on cross-linked, aliphatic polyester elastomers. Still more particularly, this invention relates to graft polymer compositions prepared by graft polymerizing a monomer mixture comprising styrene and acrylonitrile in the presence of a cross-linked, aliphatic polyester elastomer substrate.
Linear, aliphatic polyesters have been employed in the prior art as grafting substrates for a variety of vinyl monomers including styrene, acrylonitrile and the like, to prepare thermosplastic molding compositions as is disclosed, for example, in U.S. Pat. No. 3,577,478. Linear, aliphatic polyesters are also known in the art as useful plasticizers for a variety of vinyl resins such as polyvinyl chloride and polystyrene, and have been included in the preparation of an ABS resin by bulksuspension polymerization processes to impart improved processability and plasticization to the resulting ABS graft polymers, as is disclosed in U.S. Pat. No. 3,935,153. The use of linear polyesters in these prior art compositions does not appear to impart high impact characteristics without the further including of conventional diene rubber substrate and impact modifiers.